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//
// This program is a free software product.
// You can redistribute it and/or modify it under the terms
// of the GNU Affero General Public License (AGPL) version 3 as published by the Free Software
// Foundation. In accordance with Section 7(a) of the GNU AGPL its Section 15 shall be amended
// to the effect that Ascensio System SIA expressly excludes the warranty of non-infringement of
// any third-party rights.
//
// This program is distributed WITHOUT ANY WARRANTY, without even the implied warranty
// of MERCHANTABILITY or FITNESS FOR A PARTICULAR  PURPOSE. For details, see
// the GNU AGPL at: http://www.gnu.org/licenses/agpl-3.0.html
//
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//
// The  interactive user interfaces in modified source and object code versions of the Program must
// display Appropriate Legal Notices, as required under Section 5 of the GNU AGPL version 3.
//
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// distributing the program. Pursuant to Section 7(e) we decline to grant you any rights under
// trademark law for use of our trademarks.
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// All the Product's GUI elements, including illustrations and icon sets, as well as technical writing
// content are licensed under the terms of the Creative Commons Attribution-ShareAlike 4.0
// International. See the License terms at http://creativecommons.org/licenses/by-sa/4.0/legalcode

namespace ASC.Migration.Core.Models.Api;

public static class MigrationCore
{

    private static Dictionary<string, MigratorMeta> _migrators;
    private static Dictionary<string, MigratorMeta> Migrators
    {
        get
        {
            if (_migrators != null)
            {
                return _migrators;
            }

            _migrators = new Dictionary<string, MigratorMeta>(StringComparer.OrdinalIgnoreCase);

            var migratorTypes = Assembly.GetExecutingAssembly()
                .GetExportedTypes()
                .Where(t => !t.IsAbstract && !t.IsInterface
                    && typeof(IMigration).IsAssignableFrom(t));

            foreach (var type in migratorTypes)
            {
                var attr = type.GetCustomAttribute<ApiMigratorAttribute>();
                if (attr == null)
                {
                    continue;
                }

                _migrators.Add(attr.Name, new MigratorMeta(type));
            }

            return _migrators;
        }
    }

    public static string[] GetAvailableMigrations() => Migrators.Keys.ToArray();

    public static MigratorMeta GetMigrator(string migrator) => Migrators.TryGetValue(migrator, out var meta) ? meta : null;
}
